Pump



K. scHoENE PUMP` Filed April 15, 1933 Feb. 12, `1935.

Suventor o y 'ill ad y UNITED STATES PATENT OFFICE In Germany April 29,

sciaims. (ci. 10s- 202) This invention relates to pumps, and particularly to pumps of the type in which the displacing plunger overtravels inlet ports formed in the side Walls of the cylinder.

A typical example of a pump of this type is described and claimed in my prior Patent 1,760,172, May 27, 1930.

In the structure of the prior patent the inlet ports are controlled by a sleeve valve and also by the plunger. valve closes the inlet ports until the plunger overtravels the inlet ports and closes them. Shortly thereafter, and before the plunger reaches the head end dead point the sleeve valve starts to open the inlet ports, arriving at full open'position before the plunger commences to overtravel and reopen the inlet ports. From this sequence 'of operations, it follows that as soon as the plunger has overtraveled and closed the inlet ports, leakage is prevented solely by the joint between the plunger and the cylinder Walls. Heretofore this joint has been sealed by packing carried by the piston, and consequently subject to destructive wear in its passagev over the grids of the inlet ports.

The present invention provides a packing mounted in the cylinder walls and wholly inert until the plunger comes into engagement therewith. The packing is so designed as to be distended by pressure in the working space as soon as it is partially overtraveled by the plunger.

Another advantageous feature is that when the )plunger starts'itsv suction stroke and before the inlet ports are opened, the reduced pressure in the working space renders the packing inactive. In this waywear is minimized. Two embodiments of the inventionsare disclosed inA theaccompanying drawing, in which,.

Fig, 1 is a vertical axial section of the upper 46 lportieri of a cylinder and plunger'with the inven j tion applied. The plunger is shown approaching the'he'ad end dead point, thesleeve valve being about to open. n I

' Fig.2 is an enlarged vfragmentary view showing the packing illustrated in Fig. 1.

Fig. 3 is a similar view, showing a modified form of packing.

Referring first to Figs.l 1 and' 2, the cylinder wall is shown at 6 and is cast integrally with an outer sleeve 7 forming a seat for the encircling sleeve valve 8. The sleeve valve 8 controls the inlet ports 9 which are located in a circumferential series around the side walls of the cylinder.

' These ports are inclined downwardly and when exposed by downward motion of the plunger l1, direetthe entering liquid against the plunger 11,

On the discharge stroke, the sleeve y The plunger 11 has a special configuration, clearly shown in the drawing, designed to deflect the entering liquid and recover from vit a part of its kinetic energy. The particular configuration of the plunger head isnot material, but may be described as having a concave annulusv with a central projecting cone 12. This serves to reverse the direction of the entering liquid without inducing eddying.

The discharge valves 13 are of the ring type and are mounted in the cylinder head structure 14, over suitable annular ports. So far as the present invention is concerned it is immaterial whether they are provided with springs or not, but springs will commonly be used.

The packing comprises a ring 15, of rubber or like material, substantially L-shaped in cross section, and mounted in a recess provided for it inthe upper internal margin of the cylinder 6. This recess is at the junction of the cylinder with the head 14, and the packing ring may be readily removed after removal of the head. The flange 16, which gives the ring 15 its L-shaped cross sec- `tion,.projects outwardly and overhangs'the bead similar. The ring is indicated at 115 and is retained at its upper end by bead 117 'formed on the head castingl 14. It is retained at its lower margin by tongue 118 which enters an undercut in the cylinder casting. The ring 115 is tubular so thaty the annular passage 119, analogous to the space 19 already described, is formed wholly within the body of the ring 115. This space cornmunicates with the working space of the pump by means of passages 121. The two rings are functionallyA identical and the purpose of illustrating two types of ring is to make'clear the fact that the spaces 19 and 119 are functionally similar, whether formed within the body of the ring, as in Fig. 3, or wholly outside the ring, as in Figs. 1 and 2.

. It will be understood that the plunger l1 and sleeve valve 8 may be reciprocated in timed relation by any suitable means. The simplest, and l that usually adopted, comprises a crank operatciol ing the plunger 11 and two eccentrics operating the sleeve 8. The crank and ccentrics are carried bythe same shaft and are angularly so displaced from each other, that when the plunger is near the head end dead point, and has overtraveled and closed the ports 9,l the sleeve 8 will start downward and will have opened the ports 9v completely, or substantially so, when the plunger reaches and starts to open the ports 9. During the remainder of the downward (suction stroke) the'ports 9 will be opened by the sleeve valve 8, and will be closed thereby throughout the initial portion of the discharge stroke, that is, until the piston has overtraveled and closed ports 9, and has also moved into sealing engagement with the ring 15. To permit early opening of the valve 8, it is desirable that the ring be mounted as close as possible to the ports 9.

Since the plunger 1l has substantially overtraveled the ring 15 before the valve 8 has started to open, the interval between the ring and the plunger will be at suction pressure, while the space 19, 119, as the case may be, will be at discharge pressure. Consequently the ring will move into close sealing engagement with the plunger. When the plunger starts to move downward the ports 9 will be at suction .pressure while the working space above the plunger 11 will be subject to greatly reduced pressure because the plunger 11 then seeks to create a vacuum above it. Consequently, the packing 15 becomes immediately ineil'ective on the down stroke and is thus relieved of unnecessary wear.

Applicant is aware that flexible packings, distended by cylinder pressure, have been used in cylinder pumps, and does not seek broadly to claim structures of this type. .The novelty in the present case resides in the facts, ilrst, that the packing is mounted in the cylinder wall and is engaged by the plunger only at the extremity of motion oi' the plunger, and, second, that the packing is engaged by the plunger only after the plunger has overtraveled the inlet ports, one effect of which is that the packing is alternately subjected to pressure and to suction while engaged by the plunger. The invention, therefore, contemplates neither the packing per se, nor the pump per se, but the combination and coordination of these elements to produce the peculiar characteristics above described.

Various modifications are possible and are contemplated. For example, pumps having simi'- larly located inlet ports but lacking the sleeve valve 8, are known, and the use of the invention with pumps o1 this type is desirable and is contemplated.

' What is claimed is,-

l. A pump comprising in combination, a cylinv der having an inlet port and a discharge port; a discharge valve controlling the discharge port; a plunger arranged to reciprocate in the cylinder and to overtravel and close the inlet port; a packing mounted in the cylinder in position to be engaged by said plunger only when the latter has overtraveled the inlet port; and means responsive to a pressure differential between the cylinder and inlet port when cylinder pressure predominates for forcing said packing into sealing engagement with said plunger.

2. A pump comprising in combination, a cylinder= having an inlet port and a discharge port; a discharge valve controlling the discharge port; a plunger arranged to reciprocate in the cylinder and to overtravel and close the inlet port; a mechanically operated valve controlling the inlet port and moving in such timed relation tothe plunger as to close the inlet port in the ilrst portion of the -discharge stroke and open the inlet port after it has been overtraveled and closed by the plunger; a flexible packing mounted in the cylinder in position to be engaged by the plunger when the latter has closed the inlet .port; and means responsive to cylinder pressure and rendered active by the opening of the inlet valve to force said packing into sealing engagement with said plunger.

3. The combination dened in claim 2, in which the last-named means comprises a chamber bounded on its inner side by the packing and subject to pressure in the cylinder.

KURT SCHOENE. 

